1. Field of the Invention
The present invention relates to a nonvolatile memory device, a driving method thereof, and a memory system having the same.
2. Description of the Related Art
Semiconductor memory devices are microelectronic devices that are widely used in the design of digital logic circuits such as microprocessor-based applications and computers for products ranging from satellites to consumer electronics. Advances in memory fabrication technology, including technology development and process improvement obtained through scaling for high speed and high integration density, have raised the performance of digital logic systems.
Semiconductor memory devices are generally classified into volatile memory devices and nonvolatile memory devices. The nonvolatile memory devices can retain data even when power supply is disconnected. Data stored in the nonvolatile memory devices may be permanent (read only) or reprogrammable. The nonvolatile memory devices are now widely used to store executable programs or microcodes in various applications such as computers, avionics, communications, and consumer electronic technologies.
An example of the nonvolatile memory device is a flash memory device. Recently, as the demand for the high integration (miniaturization) of memory devices increases, multi-bit memory devices capable of storing multiple bits in each memory cell have become a standard commercial product.